RegiStax6

Free image
processing
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Linked Wavelet Layers (1)This
is a complete new way to use wavelets. The inventors are
Jean-Jacques Poupeau and Elie Rousset who
independently came up with this idea several years ago. Last
autumn Sylvain Weiller told me about this idea and we have
now added this as a new processing part of RegiStax.
Normally the stacked image is
"divided" over the wavelet-layers based on the gaussian sharpen filter.
When Linked Wavelet Layer is used the
stacked image is divided over the sucessive layers based on the denoise
and sharpen filters and the setting of the slider. This creates a
complete different way to sharpen the images. In this example
below we
will show/explain one of the ways to use this new tool.

The source for the images below was kindly provided by Bob Pilz,
processing was done by Cor Berrevoets.

Figure 1: the result after stacking 300 frames, the startingpoint for
wavelet enhancement
Figure 2: We have increased the sharpness/details simply by setting
slider 1 to a higher value.

Figure
3: We keep the same setting for slider 1 but now also
checkmark Linked Wavelets. Notice the difference between this
figure and figure 2, the overall sharpness and the level of
the
details (craterlets inside Plato) is a lot better.

Figure
4: Now we increase slider 2, this not only enhances details
but
cleary enhances the noise a lot too. This is typical for Linked
Wavelets, we will need to use a denoising filter to limit the noise.

Figure
5: Most of the noise will probably originate in layer 1, so we start by
activating a denoise filter in layer1 which clearly helps a
lot.

Figure
6: But Denoising layer 1 isnt enough so we also denoise layer
2
and make additional changes in the sharpen-filters to get a
reasonable balance between detail and noise.

The result after stacking
Linked Wavelets
Normal Gaussian
wavelets

This
comparison of Linked Wavelets and another processing attempt using the
same stacked image but only with Gaussian wavelets clearly shows that
Linked Wavelets can enhance the details better. Not much experimenting
has been done yet using Linked Wavelets to see which method works best
to enhance the details and at the same time keep the noise under
control. Hopefully this short description will inspire more people to
experiment with this setting.